Structural, environmental separation and HVAC items (Complex Buildings)

Last updated October 22, 2026

Values this chapter turns on

outward guard load at arena and stadium egress: 3.0 kN/m; outward guard load at arena and stadium egress
factored lateral load on a firewall under fire: 0.5 kPa; factored lateral load on a firewall under fire
indoor temperature care and residential must hold: 22°C; indoor temperature care and residential must hold
min air intake distance from a truck loading dock: 7.6 m; min air intake distance from a truck loading dock

This chapter collects the items from Parts 4, 5 and 6 that the Complex Buildings syllabus names. Part 4 gives a few design loads that a plans examiner checks on guards and firewalls. Part 5 covers the whole building envelope in performance terms. Part 6 brings in HVAC design, duct materials, air openings, venting, pipe clearances and carbon monoxide alarms. Many of these articles point to referenced standards that are not in the Compendium, so exam questions focus on the numbers and triggers the code itself states.

Loads on guards, walls acting as guards and firewalls

OBC Div. B 4.1.5.14. sets the specified live loads on guards and handrails. Outward loads are applied at the minimum required guard height.

Element	Specified live load
Guard, grandstands, stadia, bleachers, arenas, open viewing stands without fixed seats	3.0 kN/m outward
Guard, equipment platform access ways and similar areas	1.0 kN at any point
Guard, all other locations	0.75 kN/m or 1.0 kN at any point, whichever governs
Guard, inward	half the outward load
Guard, vertical at the top	1.5 kN/m
Individual guard elements (panels, pickets)	0.5 kN over 100 mm by 100 mm
Handrail, any handrail	0.9 kN at any point, any direction
Handrail, not within a dwelling unit	0.7 kN/m, any direction

The element load of 0.5 kN does not act together with the main guard loads. The vertical load does not act together with the horizontal loads.

A wall acts as a guard when the floor on one side is more than 600 mm above the floor or ground on the other side. That includes a wall around a shaft. The wall is then designed for the lateral loads in 4.1.5. or 0.5 kPa outward, whichever is more critical (4.1.5.16.).

A firewall is designed for the greater of the normal lateral loads or a factored lateral load of 0.5 kPa under fire conditions (4.1.5.17.). If the structure has a lower fire-resistance rating than the firewall, assume lateral support from one side only, or provide a support system that can resist a fire on either side.

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Environmental separation: heat, air, vapour, precipitation, ground water and sound

Part 5 applies to assemblies exposed to the exterior or the ground, and to assemblies separating dissimilar interior environments (5.1.2.1.). Its scope is condensation control and the transfer of heat, air, moisture and sound (5.1.1.1.). Above-ground climatic loads come from SB-1 (5.2.1.1.). Most requirements carry the same exemption: they can be waived where it is shown that the omission will not harm occupant health or safety, the intended use or the operation of building services.

Heat transfer (5.3.1.2.): resist heat flow enough to limit surface and internal condensation, meet interior design conditions and limit ice damming on sloped roofs.
Air leakage (5.4.1.1.): an air barrier system gives the principal resistance. It is continuous across joints, junctions and penetrations. Its assemblies meet a Performance Class from Table 5.4.1.1., which caps air leakage at a 75 Pa pressure difference. The classes run from Class 1, the tightest at 0.05 L/(s x m²), to Class 5 at 0.50 L/(s x m²).
Vapour diffusion (5.5.1.1.): a vapour barrier gives the principal resistance where temperature and vapour pressure differ across the assembly.
Precipitation (5.6.1.1., 5.6.2.1.): minimize entry into the assembly, prevent entry into the interior, and seal or drain joints.
Ground water (5.7.3.2.): assemblies against the ground are waterproofed. Dampproofing is allowed only when all three conditions in 5.7.3.4. are met: no hydrostatic pressure, a cast-in-place concrete substrate, and a drainage layer against the soil.
Sound (5.8.1.1.): a dwelling unit is separated from other noisy spaces by an ASTC of at least 47, or an STC of at least 50 with Part 9 flanking details. Against an elevator shaft or refuse chute the STC is at least 55.

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HVAC design and installation

HVAC systems follow good engineering practice, such as the ASHRAE handbooks, HRAI, SMACNA and NFPA documents (6.2.1.1.). Outdoor design conditions come from SB-1 (6.2.1.2.).

Key numbers from Section 6.2.:

Group B, Division 2 or 3 and Group C buildings used in winter must be able to hold 22°C indoors at the winter design temperature. Other buildings must hold 18°C, or a temperature suited to their use (6.2.1.1A.).
Equipment needing maintenance has access for inspection and cleaning, and mechanical equipment gets guards (6.2.1.6.).
Asbestos is banned in HVAC systems (6.2.1.7.).
Combustible pneumatic control tubing is allowed in noncombustible buildings if its outside diameter is 10 mm or less (6.2.1.8.).
Solid fuel storage bins stay below 50°C and may not sit above a sewer or drain opening (6.2.3.1.).

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Duct materials, coverings, air openings and venting

Duct materials and coverings follow the Part 3 rules in 3.6.5.1. and 3.6.5.4. (6.3.2.3., 6.3.2.5.). Linings may not interfere with dampers, fire stop flaps or other closures.

Air openings (6.3.2.9.):

Supply, return and exhaust openings less than 2 m above the floor have grilles that stop a 15 mm sphere.
Outdoor air intakes sit at least 0.3 m above roofs or grade, allowing for snow.
Intake and exhaust openings have screens with openings of 15 mm or less.
Intakes keep set distances from contaminant sources in Table 6.3.2.9.. Examples: 7.6 m from a truck loading dock, 4.5 m from garbage storage, 3.5 m from a sanitary vent and 3.0 m from a kitchen exhaust.

Venting (6.3.3.1.): appliance flue gases follow the appliance installation standards. Other vented combustion products are discharged at least:

2.15 m above sidewalks and driveways;
3 m from outdoor air intakes;
3 m from doors, operable windows and occupiable outdoor spaces.

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Piping clearances, hazardous gases and carbon monoxide alarms

Bare steam or hot water pipes need clearance from combustible material by temperature (6.7.1.2., Table 6.7.1.2.):

Water or steam temperature	Clearance
up to 95°C	none
over 95°C to 120°C	15 mm
over 120°C	25 mm

Radiator surfaces are limited to 70°C unless human contact is prevented (6.7.1.3.). Systems serving spaces with hazardous gases, dusts or liquids follow the Fire Code. An indoor trench for Class I flammable liquid piping must be ventilated to outdoors or designed against vapour build-up (6.9.1.2.). Fireplaces follow Section 9.22. (6.9.4.2.).

Carbon monoxide alarms (6.9.3.1. to 6.9.3.4.):

A residential or care suite needs CO alarms when a fuel-burning appliance or flue is in it or shares a wall, floor or ceiling with it. The same applies when a forced-air fuel-burning appliance heats it directly, or when a storage garage shares an assembly with it.
Alarms go next to each sleeping room and on each storey without one. They also go inside a sleeping room that itself shares an assembly with the appliance room or garage.
Public corridors heated directly by a forced-air fuel-burning appliance get alarms no more than 25 m apart.
In every building, service rooms with a fuel-burning appliance for building services or laundry drying get an alarm.
Alarms are hard-wired with no disconnect switch. They have battery backup for 8 h standby plus 12 h of alarm, and are interconnected within a suite and along a corridor.

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Common traps

Using 0.75 kN/m for an arena means of egress guard. Grandstands and arenas take 3.0 kN/m.
Treating the 0.5 kN element load as additive to the main guard load. The code says they do not act together.
Assuming dampproofing is fine below grade. All three conditions in 5.7.3.4. must hold.
Mixing up 15 mm grille openings (sphere test, under 2 m) with 15 mm screen mesh on outdoor openings. Both are 15 mm but apply to different openings.
Forgetting the extra CO alarm inside a sleeping room that backs onto a garage.

Chapter review

Chapter at a glance

One line per section: the idea to carry into the exam. Then the answers that most often catch candidates out.

Chapter at a glance: the key idea in each section
Section	Key idea
Loads on guards, walls acting as guards and firewalls	The element load of 0.5 kN does not act together with the main guard loads.
Environmental separation: heat, air, vapour, precipitation, ground water and sound	Part 5 applies to assemblies exposed to the exterior or the ground, and to assemblies separating dissimilar interior environments.
HVAC design and installation	HVAC systems follow good engineering practice, such as the ASHRAE handbooks, HRAI, SMACNA and NFPA documents.
Duct materials, coverings, air openings and venting	Duct materials and coverings follow the Part 3 rules in 3.6.5.1. and 3.6.5.4.. Linings may not interfere with dampers, fire stop flaps or other closures.
Piping clearances, hazardous gases and carbon monoxide alarms	Radiator surfaces are limited to 70°C unless human contact is prevented.

Loads on guards, walls acting as guards and firewalls
The element load of 0.5 kN does not act together with the main guard loads.
Environmental separation: heat, air, vapour, precipitation, ground water and sound
Part 5 applies to assemblies exposed to the exterior or the ground, and to assemblies separating dissimilar interior environments.
HVAC design and installation
HVAC systems follow good engineering practice, such as the ASHRAE handbooks, HRAI, SMACNA and NFPA documents.
Duct materials, coverings, air openings and venting
Duct materials and coverings follow the Part 3 rules in 3.6.5.1. and 3.6.5.4.. Linings may not interfere with dampers, fire stop flaps or other closures.
Piping clearances, hazardous gases and carbon monoxide alarms
Radiator surfaces are limited to 70°C unless human contact is prevented.

Usual exam traps

Using 0.75 kN/m for an arena means of egress guard. Grandstands and arenas take 3.0 kN/m.
Treating the 0.5 kN element load as additive to the main guard load. The code says they do not act together.
Assuming dampproofing is fine below grade. All three conditions in 5.7.3.4. must hold.
Mixing up 15 mm grille openings (sphere test, under 2 m) with 15 mm screen mesh on outdoor openings. Both are 15 mm but apply to different openings.
Forgetting the extra CO alarm inside a sleeping room that backs onto a garage.

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Questions on Structural, environmental separation and HVAC items, in the exam format, every answer explained and cited to its article. Sign in to start; a free account gets the free questions.

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Code cited in this chapter

Based on the official 2024 Building Code Compendium on ontario.ca.

OBC Div. B 4.1.5.14. Loads on Guards and Handrails)
(1)The minimum horizontal specified live load applied outward at the minimum required height of every required guard shall be
(a)3.0 kN/m for open viewing stands without fixed seats and for means of egress in grandstands, stadia, bleachers and arenas,
(b)1.0 kN applied at any point, so as to produce the most critical effect, for access ways to equipment platforms, contiguous stairs and similar areas where the gathering of many people is improbable, and
(c)0.75 kN/m or 1.0 kN applied at any point so as to produce the most critical effect, whichever governs for locations other than those described in Clauses (a) and (b).
(2)The minimum horizontal specified live load applied inward at the minimum required height of every required guard shall be half that specified in Sentence (1).
(3)Individual elements within the guard, including solid panels and pickets, shall be designed for a horizontal specified live load of 0.5 kN applied outward over an area of 100 mm by 100 mm located at any point on the element or elements so as to produce the most critical effect.
(4)The size of the opening between any two adjacent vertical elements within a guard shall not exceed the limits required by Part 3 when each of these elements is subjected to a horizontal specified live load of 0.1 kN applied in opposite directions in the in-plane direction of the guard so as to produce the most critical effect.
(5)The specified live loads required in Sentence (3) need not be considered to act simultaneously with the loads provided for in Sentences (1), (2), (6) and (7).
(6)The minimum specified live load applied vertically at the top of every required guard shall be 1.5 kN/m and need not be considered to act simultaneously with the horizontal specified live load provided for in Sentences (1), (3) and (7).
(7)Handrails and their supports shall be designed and constructed to withstand the following minimum specified live loads, which need not be considered to act simultaneously:
(a)0.9 kN applied at any point and in any direction for all handrails, and
(b)0.7 kN/m applied in any direction for handrails not located within dwelling units.
Open OBC Div. B 4.1.5.14. in the code viewer
OBC Div. B 4.1.5.16. Loads on Walls Acting As Guards
(1)Where the floor elevation on one side of a wall, including a wall around a shaft, is more than 600 mm higher than the elevation of the floor or ground on the other side, the wall shall be designed to resist the appropriate outward lateral design loads prescribed elsewhere in Subsection 4.1.5. or 0.5 kPa acting outward, whichever produces the more critical effect.
Open OBC Div. B 4.1.5.16. in the code viewer
OBC Div. B 4.1.5.17. Firewalls
(1)Firewalls shall be designed to resist the maximum effect due to,
(a)the appropriate lateral design loads prescribed elsewhere in this Section, or
(b)a factored lateral load of 0.5 kPa under fire conditions, as described in Sentence (2).
(2)Under fire conditions, where the fire-resistance rating of the structure is less than that of the firewall,
(a)lateral support shall be assumed to be provided by the structure on one side only, or
(b)another structural support system capable of resisting the loads imposed by a fire on either side of the firewall shall be provided.
Open OBC Div. B 4.1.5.17. in the code viewer
OBC Div. B 5.1.2.1. Exposure to Exterior Space or the Ground and Separation of Dissimilar Environments
(1)This Part applies to
(a)building materials, components and assemblies exposed to exterior space or the ground, including those separating interior space from exterior space or separating interior space from the ground,
(b)building materials, components and assemblies separating environmentally dissimilar interior spaces, and (See Note A-5.8.)
(c)site materials, components, assemblies and grading that may affect environmental loads on building materials, components and assemblies exposed to exterior space or the ground. (See Note A-5.1.2.1.(1))
Open OBC Div. B 5.1.2.1. in the code viewer
OBC Div. B 5.1.1.1. Scope
(1)This Part is concerned with
(a)the control of condensation
(i)in building components and assemblies, and
(ii)on building materials, components and assemblies, and
(b)the transfer of heat, air, moisture and sound through
(i)building materials, components and assemblies, and
(ii)interfaces between building materials, components and assemblies. (See Note A-5.1.1.1.(1))
Open OBC Div. B 5.1.1.1. in the code viewer
OBC Div. B 5.2.1.1. Exterior Environmental Loads
(1)Above ground climatic loads shall be determined according to MMAH Supplementary Standard SB-1, "Climatic and Seismic Data."
(2)Except as provided in Sentence (3), below ground exterior environmental loads not described in MMAH Supplementary Standard SB-1, "Climatic and Seismic Data," shall be determined from existing geological and hydrological data or from site tests.
(3)Where local design and construction practice has shown soil temperature analysis to be unnecessary, soil temperatures need not be determined. (See Note A-5.2.1.1.(3))
Open OBC Div. B 5.2.1.1. in the code viewer
OBC Div. B 5.3.1.2. Properties to Resist Heat Transfer or Dissipate Heat
(1)Taking into account the conditions on either side of the environmental separator, materials and components installed to provide the required resistance to heat transfer or the means implemented to dissipate heat shall provide sufficient resistance or dissipation,
(a)to minimize surface condensation on the warm side of the component or assembly,
(b)in conjunction with other materials and components in the assembly, to minimize condensation within the component or assembly,
(c)in conjunction with systems installed for space conditioning, to meet the interior design thermal conditions for the intended occupancy, and
(d)to minimize ice damming on sloped roofs. (See Note A-5.3.1.2.(1))
Open OBC Div. B 5.3.1.2. in the code viewer
OBC Div. B 5.4.1.1. Required Resistance to Air Leakage (Note A-5.4.1.1.)
(1)Where a building component or assembly separates interior conditioned space from exterior space, interior space from the ground, or environmentally dissimilar interior spaces, the properties and position of the materials and components in those components or assemblies shall be such that they control air leakage or permit venting to the exterior so as to
(a)provide acceptable conditions for the building occupants,
(b)maintain appropriate conditions for the intended use of the building,
(c)minimize the accumulation of condensation in and the penetration of precipitation into the building component or assembly,
(d)control heat transfer to roofs where ice damming can occur,
(e)minimize the ingress of airborne radon and other soil gases from the ground with an aim to controlling the indoor concentrations of these gases to an acceptable level, and
(f)not compromise the operation of building services.
(2)Except as provided in Sentence (7), an air barrier system shall be designed and constructed to provide the principal resistance to air leakage to meet the requirements of Sentence (1).
(3)The air barrier system shall incorporate air barrier assemblies that meet the appropriate Performance Class as defined in Table 5.4.1.1. (See Note A-5.4.1.1.(3))
(4)The air barrier system shall be designed and constructed to be continuous
(a)across construction, control and expansion joints,
(b)across junctions between different air barrier assemblies, and
(c)around penetrations through air barrier assemblies. (See Note A-5.4.1.1.(4))
(5)The structural design of air barrier assemblies, including junctions between air barrier assemblies, subject to air pressure loads shall comply with Article 5.1.4.1. and Subsection 5.2.2.
(6)The maximum air leakage rates specified in Table 5.4.1.1. are permitted to be increased where it can be shown that the higher rate will not adversely affect any of
(a)the health or safety of the building users,
(b)the intended use of the building, or
(c)the operation of building services.
(7)An air barrier system is not required where it can be shown that uncontrolled air leakage will not adversely affect any of
(a)the health or safety of building users,
(b)the intended use of the building, or
(c)the operation of building services. (See Note A-5.4.1.1.(7))
Open OBC Div. B 5.4.1.1. in the code viewer

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OBC Div. B Table 5.4.1.1. Maximum Air Leakage Rates for Air Barrier Assemblies — Forming Part of Sentences 5.4.1.1.(3) and (6) and 5.4.1.2.(1) and (2)
Table 5.4.1.1. Maximum Air Leakage Rates for Air Barrier Assemblies — Forming Part of Sentences 5.4.1.1.(3) and (6) and 5.4.1.2.(1) and (2) Performance Class | Maximum Air Leakage Rate, L / (s × m²), at a Pressure Differential of 75 Pa 1 | 0.05 2 | 0.10 3 | 0.15 4 | 0.20 5 | 0.50
Open OBC Div. B Table 5.4.1.1. in the code viewer
OBC Div. B 5.5.1.1. Required Resistance to Vapour Diffusion
(1)Where a building component or assembly is subjected to differentials in temperature and water vapour pressure, the properties and position of the materials and components in those components or assemblies shall be such that they control vapour diffusion or permit venting to the exterior so as to minimize accumulation of condensation in the building component or assembly.
(2)Except as provided in Sentence (3), a vapour barrier shall be installed to provide the principal resistance to water vapour diffusion.
(3)A vapour barrier is not required where it can be shown that uncontrolled vapour diffusion will not adversely affect any of
(a)the health or safety of building users,
(b)the intended use of the building, or
(c)the operation of building services.
Open OBC Div. B 5.5.1.1. in the code viewer
OBC Div. B 5.6.1.1. Required Protection from Precipitation
(1)Except as provided in Sentence (2), where a building component or assembly is exposed to precipitation, the component or assembly shall
(a)minimize ingress of precipitation into the component or assembly, and
(b)prevent ingress of precipitation into interior space.
(2)Protection from ingress of precipitation is not required where it can be shown that such ingress will not adversely affect any of
(a)the health or safety of building users,
(b)the intended use of the building, or
(c)the operation of building services.
Open OBC Div. B 5.6.1.1. in the code viewer
OBC Div. B 5.6.2.1. Sealing and Drainage
(1)Except as provided in Sentence (2), materials, components, assemblies, joints in materials, junctions between components and junctions between assemblies exposed to precipitation shall be
(a)sealed to prevent ingress of precipitation, or
(b)drained to direct precipitation to the exterior.
(2)Sealing or drainage are not required where it can be shown that the omission of sealing and drainage will not adversely affect any of,
(a)the health or safety of building users,
(b)the intended use of the building, or
(c)the operation of building services.
Open OBC Div. B 5.6.2.1. in the code viewer
OBC Div. B 5.7.3.2. Required Protection
(1)Except as provided in Sentence (2) and Article 5.7.3.4., building assemblies described in Article 5.7.3.1. shall be protected by waterproofing in accordance with Article 5.7.3.3. so as to minimize the ingress of water into the building or the accumulation of water against the building.
(2)Waterproofing is not required where it can be shown that
(a)a building is designed to accommodate the ingress or accumulation of ground water, or
(b)the ingress or accumulation of ground water will not negatively affect
(i)the health or safety of building users,
(ii)the intended use of the building, or
(iii)the operation of building services.
Open OBC Div. B 5.7.3.2. in the code viewer
OBC Div. B 5.7.3.4. Where Dampproofing is Permitted
(1)Vertical building assemblies that separate interior space from the ground are permitted to be dampproofed where,
(a)such assemblies are not subjected to hydrostatic pressure,
(b)the substrate is cast-in-place concrete, and
(c)a drainage layer is installed between the building assembly and the soil.
(See Note A-5.7.3.4.(1))
(2)Joints, junctions and penetrations shall be designed and constructed to maintain the continuity of the dampproofing.
Open OBC Div. B 5.7.3.4. in the code viewer
OBC Div. B 5.8.1.1. Required Protection
(1)Except as provided in Sentence (2), a dwelling unit shall be separated from every other space in a building in which noise may be generated by
(a)a separating assembly and adjoining constructions, which, together, provide an apparent sound transmission class (ASTC) rating not less than 47, or
(b)a separating assembly that provides a sound transmission class (STC) rating of not less than 50 and adjoining constructions that conform to Article 9.11.1.4.
(2)Construction separating a dwelling unit from an elevator shaft or a refuse chute shall have an STC rating not less than 55.
Open OBC Div. B 5.8.1.1. in the code viewer
OBC Div. B 6.2.1.1. Good Engineering Practice
(1)Heating, ventilating and air-conditioning systems, including mechanical refrigeration equipment, shall be designed, constructed and installed in conformance with good engineering practice such as that described in, but not limited to,
(a)the ASHRAE Handbooks and Standards,
(b)the HRAI Digest,
(c)the Hydronics Institute Manuals,
(d)the NFPA Standards,
(e)the SMACNA Manuals,
(f)the ACGIH manual entitled "Industrial Ventilation: A Manual of Recommended Practice for Design,"
(g)CSA B214, "Installation code for hydronic heating systems,"
(h)CAN/CSA-Z317.2, "Special requirements for heating, ventilation, and air-conditioning (HVAC) systems in health care facilities,"
(i)EPA 625/R-92/016, "Radon Prevention in the Design and Construction of Schools and Other Large Buildings," and
(j)ASHRAE Guideline 12, "Minimizing the Risk of Legionellosis Associated with Building Water Systems."
Open OBC Div. B 6.2.1.1. in the code viewer
OBC Div. B 6.2.1.2. Outdoor Design Conditions
(1)The outdoor conditions to be used in designing heating, ventilating and air-conditioning systems shall be determined in conformance with MMAH Supplementary Standard SB-1, "Climatic and Seismic Data."
Open OBC Div. B 6.2.1.2. in the code viewer
OBC Div. B 6.2.1.1A. Design Indoor Air Temperatures
(1)Buildings classified as Group B, Division 2 or 3 occupancies or Group C residential occupancies that are intended for use in the winter months on a continuing basis shall be insulated and be equipped with heating facilities that are capable of maintaining an indoor air temperature of 22°C at the outside winter design temperature referred to in Article 6.2.1.2.
(2)All other buildings intended for occupancy in the winter months on a continuing basis should be insulated and shall be equipped with heating facilities to maintain a minimum indoor air temperature of 18°C or commensurate with the use of the building at the outside winter design temperature described in Article 6.2.1.2.
Open OBC Div. B 6.2.1.1A. in the code viewer
OBC Div. B 6.2.1.6. Installation — General
(1)Equipment requiring periodic maintenance and forming part of a heating, ventilating or air-conditioning system shall be installed with provision for access for inspection, maintenance, repair and cleaning. (See Note A-6.2.1.6.(1))
(2)Mechanical equipment shall be provided with guards so as to prevent injury.
(3)Heating, ventilating or air-conditioning systems shall be protected from freezing if they may be adversely affected by freezing temperatures.
Open OBC Div. B 6.2.1.6. in the code viewer
OBC Div. B 6.2.1.7. Asbestos
(1)Asbestos shall not be used in heating, ventilating or air-conditioning systems or equipment.
Open OBC Div. B 6.2.1.7. in the code viewer
OBC Div. B 6.2.1.8. Combustible Tubing
(1)Combustible tubing for pneumatic controls may be used in buildings required to be of noncombustible construction provided it has an outside diameter not exceeding 10 mm.
Open OBC Div. B 6.2.1.8. in the code viewer
OBC Div. B 6.2.3.1. Solid Fuel Storage Bins
(1)A storage bin for solid fuel shall not be located above a sewer opening or drain opening.
(2)Storage bins for solid fuel shall be designed and constructed so that the air temperature in the bin or the surface temperature of any part of the floor or walls is below 50°C.
Open OBC Div. B 6.2.3.1. in the code viewer
OBC Div. B 6.3.2.3. Materials in Air Duct Systems
(1)All ducts, duct connectors, associated fittings and plenums used in air duct systems shall be constructed of materials as described in Article 3.6.5.1.
(2)Ducts that are used in a location where they may be subjected to excessive moisture shall have no appreciable loss of strength when wet and shall be resistant to moisture-induced corrosion.
(3)All ductwork and fittings shall be constructed and installed as recommended in SMACNA Manuals and ASHRAE Standards.
(4)All duct materials shall be suitable for exposure to the temperature and humidity of the air being carried and shall be resistant to corrosion caused by contaminants in the air being conveyed in the duct.
Open OBC Div. B 6.3.2.3. in the code viewer
OBC Div. B 6.3.2.5. Duct Coverings, Linings, Adhesives and Insulation
(1)Coverings, linings and associated adhesives and insulation used in air ducts, plenums and other parts of air duct systems shall comply with Article 3.6.5.4.
(2)Duct linings shall be installed so that they will not interfere with the operation of volume or balancing dampers or of fire dampers, fire stop flaps and other closures.
Open OBC Div. B 6.3.2.5. in the code viewer
OBC Div. B 6.3.2.9. Supply, Return, Intake and Exhaust Air Openings
(1)Supply, return and exhaust air openings located less than 2 m above the floor in rooms or spaces in buildings shall be protected by grilles having openings of a size that will not allow the passage of a 15 mm diam sphere.
(2)Outdoor air intakes shall be located so that
(a)the quality of the air entering the building complies with Sentence 6.2.1.2.(1), and
(b)they are separated a minimum distance from sources of contaminants in accordance with Table 6.3.2.9.
(3)Outdoor air intakes shall be installed not less than 0.3 m above roofs, landscape grades or other surfaces, taking into account anticipated snow accumulation levels.
(4)Exterior openings for outdoor air intakes and exhaust outlets shall be shielded from the entry of snow and rain and shall be fitted with corrosion-resistant screens of mesh having openings not larger than 15 mm, except where experience has shown that climatic conditions require larger openings to prevent the screen openings from icing over.
(5)Screens required in Sentence (4) shall be accessible for maintenance.
(6)Combustible grilles, diffusers and other devices covering supply, return, intake and exhaust openings shall comply with Article 3.6.5.7.
Open OBC Div. B 6.3.2.9. in the code viewer
OBC Div. B Table 6.3.2.9. Minimum Distances of Air Intakes from Sources of Contaminants — Forming Part of Sentence 6.3.2.9.(2)
Table 6.3.2.9. Minimum Distances of Air Intakes from Sources of Contaminants — Forming Part of Sentence 6.3.2.9.(2) Source of Contaminants | Minimum Distance of Outdoor Air Intake, m Garage entry of a garage for 5 or more motor vehicles, automobile loading area and drive-in queue | 4.5 Truck loading area or dock, and bus parking | 7.6 Driveway, parking space, lane, road and similar locations that carry a low volume of traffic | 1.5 Thoroughfare, arterial road, freeway, highway and similar locations that carry a high volume of traffic | 7.6 Garbage storage/pick-up area and dumpsters | 4.5 Discharge from evaporative heat rejection systems | 7.6 Sanitary vent | 3.5 Kitchen exhaust outlet | 3.0 Vent for combustion products from solid fuel-burning appliances | 3.0
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OBC Div. B 6.3.3.1. Requirement for Venting
(1)Except as provided in Articles 6.3.3.2. and 6.3.3.3., the products of combustion from oil-, gas and solid-fuel-burning appliances shall be vented in conformance with the requirements in the applicable appliance installation standard listed in Article 6.2.1.5.
(2)Except as provided in Article 6.2.1.5., vented products of combustion, other than those referred to in Sentence (1), shall be discharged away from the building, so as not to re-enter it, to a distance not less than
(a)2.15 m above sidewalks and driveways,
(b)3 m from outdoor air intakes,
(c)3 m horizontally or vertically from doors and operable windows, and
(d)3 m horizontally or vertically from occupiable outdoor spaces, excluding maintenance spaces. (See Note A-6.3.3.1.(2))
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OBC Div. B 6.7.1.2. Clearances
(1)Clearances between combustible material and bare pipes carrying steam or hot water shall conform to Table 6.7.1.2.
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OBC Div. B Table 6.7.1.2. Clearance Between Steam or Hot Water Pipes and Combustible Material — Forming Part of Article 6.4.2.1., Sentence 6.4.3.1.(2) and Article 6.7.1.2.
Table 6.7.1.2. Clearance Between Steam or Hot Water Pipes and Combustible Material — Forming Part of Article 6.4.2.1., Sentence 6.4.3.1.(2) and Article 6.7.1.2. Steam or Water Temperature, °C | Minimum Clearance, mm Up to 95 | No clearance Above 95 to 120 | 15 mm Above 120 | 25 mm
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OBC Div. B 6.7.1.3. Surface Temperature
(1)The exposed surface temperature of a steam or hot water radiator shall not exceed 70°C unless precautions are taken to prevent human contact. (See Note A-6.5.1.1.(3))
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OBC Div. B 6.9.1.2. Hazardous Gases, Dusts or Liquids
(1)Except as provided in Subsection 6.3.4., systems serving spaces that contain hazardous gases, dusts or liquids shall be designed, constructed and installed in conformance with the provisions of the Fire Code made under the Fire Protection and Prevention Act, 1997, or in the absence of requirements pertinent to such systems in the Fire Code, to good engineering practice such as that described in the publications of the National Fire Protection Association and in the CCBFC NRCC-CONST-56437E, "National Fire Code of Canada. (See Note A-6.9.1.2.(1))
(2)When indoor piping for Class I flammable liquids is installed in a trench, the trench shall be
(a)provided with positive ventilation to the outdoors, or
(b)designed to prevent the accumulation of flammable vapours.
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OBC Div. B 6.9.4.2. Fireplaces
(1)Fireplaces shall conform to the requirements of Section 9.22.
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OBC Div. B 6.9.3.1. Application
(1)Article 6.9.3.2. applies to every building that
(a)contains a residential occupancy, a care occupancy with individual suites, or a care occupancy containing sleeping rooms not within a suite, and contains a fuel-burning appliance or a storage garage, or
(b)contains a residential occupancy and is served by a forced-air fuel-burning appliance not contained within the building.
(2)Articles 6.9.3.3. and 6.9.3.4. apply to every building.
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OBC Div. B 6.9.3.4. Installation and Conformance to Standards
(1)The carbon monoxide alarms required by Articles 6.9.3.2. and 6.9.3.3. shall
(a)except as permitted in Sentence (2), be permanently connected to an electrical circuit and shall have no disconnect switch between the overcurrent device and the carbon monoxide alarm,
(b)in case the regular power supply to the carbon monoxide alarm is interrupted, be provided with a battery as an alternative power source that can continue to provide power to the carbon monoxide alarm for a period of not less than 8 h in the standby condition, followed by the operation of the carbon monoxide alarm for an alarm signal for at least 12 h,
(c)be wired so that
(i)activation of one carbon monoxide alarm within a suite of residential occupancy will activate all carbon monoxide alarms within the suite, and
(ii)activation of one carbon monoxide alarm located in a public corridor serving suites of residential occupancy will activate all carbon monoxide alarms within the corridor,
(d)be audible within sleeping rooms when the intervening doors are closed, where located adjacent to a sleeping room in a suite of residential occupancy, and
(e)conform to
(i)CAN/CSA-6.19, "Residential Carbon Monoxide Alarming Devices", or
(ii)UL 2034, "Single and Multiple Station Carbon Monoxide Alarms".
(2)Where the building is not supplied with electrical power, carbon monoxide alarms are permitted to be battery operated.
(3)Except as permitted in Sentence (4), the carbon monoxide alarms required by Articles 6.9.4.2. and 6.9.4.3. shall have a visual signalling component conforming to the requirements in 18.5.3. (Light, Color and Pulse Characteristics) of NFPA 72, "National Fire Alarm and Signaling Code".
(4)Where the building is not supplied with electrical power, carbon monoxide alarms need not have a visual signalling component.
(5)The luminous intensity for visual signalling components required by Sentence (3) that are installed in sleeping rooms or combined living and sleeping areas shall be a minimum of 175 cd.
(6)The visual signalling component required by Sentence (3) need not
(a)be integrated with the carbon monoxide alarm provided it is interconnected to it,
(b)be on battery backup, or
(c)have synchronized flash rates, when installed in a dwelling unit.
(7)The carbon monoxide alarms required by Articles 6.9.3.2. and 6.9.3.3. shall be installed
(a)at the manufacturer's recommended height, or
(b)in the absence of specific instructions, on or near the ceiling.
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